Other than that, you can prepare a simple notice letting them know that you thank them for applying, however they did not meet the criteria, and you can choose to tell them it was based off of their credit, and or background or simply just say that the minimum requirements were not met. 

Eric, I hope that wasn't too simple of an answer. 

Very simple as Chris notes its just an up front agreement..

I'm quickly learning that getting a mortgage isn't a simple task.

Each lender will be willing to provide a ballpark rate quote with some simple info such as FICO score, property type, location, term, and desired LTV.

Very simple way to take 1003s.

The process is easy:1) You’ll receive a disarmingly simple one-inch-thick three-ring binder containing your plan documents.

This simple update has big implications for property owners, allowing small repairs and maintenance to be handled more quickly and affordably.

It's not simple, it's not easy and it sure as hell isn't a sure thing. 

Tools like Lodgify or Hostaway make it simple to integrate booking and payment options.